/*
 * Copyright (c) 2010 Mathew Hall, University of Sheffield.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following conditions
 * are met:
 *
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * Neither the name of the University of Sheffield nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
package gpinterpreter;

import gpinterpreter.vector.VecInstruction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import static gpinterpreter.vector.VecSymbol.*;

/**
 * Parse a String program into a list of Instructions.
 * This class is only useful for deserialisation.
 * @author mat
 *
 */
public abstract class GPParser {
	
	public static List<VecInstruction> parse(String program) throws ParseErrorException{
		String[] lst = program.split("[ \t\n\r]+");
		
		ArrayList<VecInstruction> p = new ArrayList<VecInstruction>();
		do{
			Tuple<VecInstruction,String[]> res = parseExpr(lst);
			
			p.add(res.fst());
			lst = res.snd();
		}while(lst.length != 0);
		return p;
	}
	
	private static Tuple<VecInstruction,String[]> parseExpr(String[] tokens) throws ParseErrorException{
		if(tokens[0].equals("NOP") || tokens[0].equals(""))
			return new Tuple<VecInstruction,String[]>(new VecInstruction(NOP),Arrays.copyOfRange(tokens,1, tokens.length));
		
		if(tokens[0].equals("SPLIT")){
			int operand1;
			try{
				operand1 = Integer.parseInt(tokens[1]);
			}catch(Exception e){
				throw new ParseErrorException("parse failed on operands of SPLIT " + tokens[1]);
			}
			return new Tuple<VecInstruction,String[]>(new VecInstruction(SPLIT,operand1),Arrays.copyOfRange(tokens,2, tokens.length));
			
		}
		
		if(tokens[0].equals("MERGE")){
			//tokens = Arrays.copyOfRange(tokens,1, tokens.length);
			int operand1, operand2;
			try{
				operand1 = Integer.parseInt(tokens[1]);
				operand2 = Integer.parseInt(tokens[2]);
			}catch(Exception e){
				throw new ParseErrorException("parse failed on operands of MERGE " + tokens[1] + " " + tokens[2]);
			}
			return new Tuple<VecInstruction,String[]>(new VecInstruction(MERGE,operand1,operand2),Arrays.copyOfRange(tokens,3, tokens.length));
			
		}
			
		if(tokens[0].equals("MOVE")){
			int operand1, operand2;
			try{
				operand1 = Integer.parseInt(tokens[1]);
				operand2 = Integer.parseInt(tokens[2]);
			}catch(Exception e){

				String toks = "";
				for(String s : tokens) toks += ","+s;
				throw new ParseErrorException("parse failed on operands of MOVE " + tokens.length + "[" + toks +"]" );
				
			}
			return new Tuple<VecInstruction,String[]>(new VecInstruction(MOVE,operand1,operand2),Arrays.copyOfRange(tokens,3, tokens.length));
			
		}
		
		throw new ParseErrorException("Unexpected symbol <" + tokens[0] + ">");
	}

}
